Apparatus for maintaining optimum conditions in gaseous mediums



Aug. 31, 1948. J, TURNER r 2,448,403

APPARATUS FOR MAINTAINING OPTIMUM v CONDITIONS IN GASEOUS IEDIUMS FiledNov. 11, 1943 5 Shasta-Shut 1 Manta? J .4 W128? fl- 1943- J. L. TURNERAPPARATUS FOR IAINTAINING OPTIMUM CONDITIONS 1 GASEOUS IEDIUIS Filed Nov11, 1943 3 Shoots-Shoot 2 Aug. 31, 1948. J L Tm 2,448,403.

APPARATUS FORHIAINTAINING OPTIMUM CONDITIONS IN GASEOUS IEDIUIIS FiledNov. 11, 1943 3 su s-$1.4 a

Patented Aug. 31, 1948 APPARATUS FOR MAINTAINING CONDITIONS IN GASEOUSMEDIUMS Ms L. Turner, Norwell, Mam, alsignor to Mannlng, Maxwell &Moore, Incorporated, New York, N. Y., a corporation of New JerseyApplication November 11, 1943, Serial No. 509,856

8 cum. 1

This invention relates to control apparatus, and

more particularly to apparatus which is sensitively responsive to thepresence of small particles, solid or liquid, in a gaseous medium, forinstance a normally superheated vapor.

In many rocesses and types of apparatus d a ing with gases or vapors,for example in gas puriflcation; in the employment of dry saturatedsteam or superheated or other vapors, for ex-' ample in steamengineering; in chemical processes; for mechanical purposes; inrefrigeration,

etc., it would frequently be of great advantage if the presence of solidparticles or liquid droplets in the gaseous medium could be caused tomanifest itself automatically either by the actuation of a signal or byinitiatingthe operation of valves or other devices designedautomatically to restore conditions to normal or to stop furtheroperation until normal conditions have been otherwise restored.

2 in the hollow body, and therebyoperates or causes to operate anappropriate regulating means, signal, or other apparatus. This hollowbody-or boiler is normally maintained at a temperature slightlydifferent from that of the gaseous medium in the container or conduit,for example the hollow body may be heated electrically or it I may berefrigerated by a refrigerating fluid.

It is well recognized that heat is transferred more rapidly between twosolids or. a solid and a liquid than between a solid and a gaseousmedium (gas or true vapor). In accordance with the present inventionthis principle is made use of to determine for instance the presence ofsolid particles (dust) in a gas; the presence of un-- desired dropletsof water, oil or the like in a dry sible, as a practical matter, todetermine the presence, by automatic means, of such solid particles ordroplets of liquid or to provide. for the automatic operation ofregulating or controlling means, for instance means for so varyingcondi-- tions as to prevent the. introduction or formation of suchdroplets of liquid.

In accordance with the present invention, there is disposed within thecontainer for the gaseous medium, for instance a conduit through whichthe gaseous medium flows, a hollow body (hereinafter referred to as aboiler) containing a fluid medium which volatilizes and condenses, orwhich expands and contracts very rapidly in response to temperaturechange. The interior of this hol- 7 low body or boiler communicates witha device in which a part or element moves in response "to the varyingpressure exerted by the fluid medium Whatever means beprovided fornormally maintaining the desired temperature differential, said meansshould preferably be responsivelysensitive to variations in pressure ortemperature of the gaseous medium in the container in order that suchtemperature differential may be kept constant.

The heat input (or withdrawal) should be such as to cOmpensatefOr heatlosses in the connections and by reason of any circulation of the fluidin the hollow body or boiler or in the passages leading therefrom, andunder normal and proper conditions (degree of purity, wetness,superheat, or the like) of the gaseous medium, to keep the hollow bodyor boiler at a temperature slightly different (whether warmer or cooler)than that of the gaseous medium. Assuming the maintenance of such anormal temperature differential, the presence of solid particles orliquid droplets (even though such particles or droplets be at the sametemperature as the gaseous medium in which they are suspended) isimmediately manifest, since upon impact or contact of such particles ordroplets upon or with the shell of the boiler there is a suddenvariation in the rate of transfer of heat to or from the boiler shell.The fluid within the boiler shell thereupon contracts or expands, andthe variation in pressure thus occasioned at the motor or other controldevice actuates the latter, thereby for example, correcting thecondition .of the gaseous medium; actuating a signal, or affecting theoperation of apparatus in which the gaseous medium is' employed.

The present invention has for one of its principal objects the provisionof means which is very sensitively responsive to the presence of solidparticles or liquid droplets in a gaseous medium, and which by itsresponse thereto may be made to accomplish corrective results or toactuate a signal or the like.

In refrigerating systems of the compression type it is highly importantto maintain the fluid in the suction line in a dry saturated or slightlysuperheated condition, since any departure from such condition, withconcomitant formation of droplets in the flowing fluid is not onlyuneconomical f' cm the thermodynamic standpoint but also may esult inmechanical damage to the compressor, since the presence of highlyincompressibie liquid in the compressor cylinder may result in crackingor blowing oi! the cylinder head. A further and more specific object ofthe present invention is to provide control means for use in arefrigerating system, said control means including an element which issensitively responsive to the presence of droplets of liquid in thesuction This expansion valve (Fig. 2) may be of any coil l beingconnected, through the pipes I6 in order to maintain a predeterminedoptimum variations in the pressure and temperature in the suction line.Other and further objects and advantages of the invention will bepointed out in the following more detailed descriptionand by referenceto the accompanying drawings, wherein- Fig. 1 is a diagram illustratinga refrigerating system of the compression type embodying the presentinvention;

Fig. 2 is a vertical section, to larger scale, illustrating the pressuremotor actuated expansion valve of Fig. 1;

Fig. 3 is a fragmentary diagrammatic view 11- I lustrating amodification of the control apparatus shown in Fig. 1;

Fig. 4 is a fragmentary diagrammatic view 11- lustrating a furthermodification of the control apparatus;

Fig. 5 is a diagrammatic elevation showing the principle of the presentinvention as applied to the operation of indicating means;

' Fig. 6 is a similar view but showing a control embodying electronicfeature;

Fig. 7 is a modified type of control in which the sensitive element isrefrigerated; and

Fig. 8 is a diagram illustrating the pressuretemperature relation atconstant volume of two common refrigerating fluids. Referring to thedrawings and particularly to Fig. 1, the numeral l designates anelectrically driven compressor of conventional type, either single stageor multiple stage, having the high pressure delivery pipe 2 which leadsto the receiving end of the condensing coil 3. This coil is cooled, forexample, by a water spray, and the refrigerating medium, thus condensedto a liquid, fiows into the closed chamber 4 in the lower part of thecondenser. The outlet I fromthis chamber 4 is preferably, in accordancewith the present invention, controlled by a float-actuated valve 6,which only opens to permit liquid to escape when the liquid level in thechamber 4 reaches a predetermined height. A high pressure pipe 8 leadsfrom the delivery orifice 5 to the pressure-motor actuated expansionvalve V. The expansion valve V has a seat or orifice .which iscontrolled by a valve 9 having a stem 9 whose lower end is connected tothe head 9 of a metallic bellows III. A spring Ii tends to close thevalve 9. The bellows I0 is housed in I .a fluid tight casing l3 and thespace within this .c'asing (outside of the bellows defines the exandii", to the suction side of the compressor,

so that in the pipes l6 and 16 a low pressure is always maintained-thecompressor thus being interposed between the low and high pressure sidesof the system. a

In accordance with the present invention and working condition of therefrigerating medium in the low pressure side of the system, anautomatic controller K is interposed between the pipe sections l6 andI6. As shown in Fig. 1, this controller comprises a casing or housingll, of somewhat larger diameter than the pipe I, within which is placeda thin-walled hollow bulb or capsule I 8 (the boiler above referred to)of a material which is a very good conductor of heat. Capillary tubes l9and 20 lead from the opposite ends of this bulb 0r capsule I8. The outerend of the tube 20 is connected to a coil 2| of metal tubing which isresistant to electric current and preferably electrically insulated atits opposite.

ends from other metallic parts. The opposite ends of this coil 2| areconnected to the terminals of the secondary 22 of a transformer 23. Theupper ends of tube l9 and coil 2|, as shown in Fig. l, are united andconnected by a pipe 24 to the pressure chamber I2 of the expansion valveV.

The bulb or capsule IS, the tubes is and 20. the coil 2i, the. pipe 24and the motor chamber l2 of the valve V are normally filled with aliquid which is very volatile and whose pressure thus varies veryquickly in response to temperature change.

Preferably a pressure-sensitive circuit controller 25 is mounted on thecasing IT. This pressure-sensitive circuit controller may be ofconventional type, for example an instrument including a sensitiveBourdon tube as a pressure motor means or a diaphragm or its equivalent.This device may be of the type in which a lever contact movessuccessively over a series of contacts connected to taps on a resistor,or it may be a device which varies the flow of current by changing thetotal impedance in the circuit. Whatever the exact nature of ,the device25 may be, it is connected in' series with the primary 26 of thetransformer 23 and also in series with the coil of a relay 28. The relayactuates a switch, 21, which controls the energizing circuit of thecompressor motor. When current flows through the primary 26 of thetransformer, heating current is thereby caused to'flow through thetubular resistance coil 2| soas to heat the volatile fluid in the coilandthus heat the fluid in the bulb or boiler l8. However, the intensityof current flow through the primary 26 will depend upon the setting ofthe pressure-responsive circuit controller 25, so that the temperatureof the fluid medium in the bulb ill will vary in accordance with thepressure in the suction line i6. By proper adjustment of the instrument25 it is thus possible to maintain the fluid within the bulb ill at atemperature, which, in accordance with the present invention, should bevery slight 1y higher (for'example, from 3 to 12 F.) than relay currentis energized, it closes the switch.

21 which starts the motor. It will be noted that byreason oi theprovision of the float-actuated valve 8 in the high pressure side of thesystem, it is impossible for refrigerating fluid in the gaseous state toenter the expansion valve.

Assuming that the switch 21* has been closed and the compressor startedand that there is condensed refrigerating fluid in the chamber 4suillclent to open the valve 8, some of this fluid flows to the valve Vand is permitted by the latter to enter the pipe It, the degree to whichthe expansion valve 9 is lifted from its seat determining the rate atwhich the liquid may enter the expansion coil is. The pump maintainssuction in the expansion coil II and also in the pipe IS, the casing i1and the pipe it, thus causing the expanded refrigerating medium in a'gaseous or diii'erentlal between the contents oi the bulb II and thesurrounding gaseous mediim'i (as determined by the heating effect of thecurrent supplied by the transformer 23) remains nearly constant.However, substantially instantly upon the appearance oi droplets ofliquid in the flowing gaseous medium, the temperature of the bulb l8 andits contents will be reduced by reason or the more rapid transfer ofheat between the liquid droplets and the metal of the bulb than betweenthe dry gas and the metal oi the bulb (although the droplets may be atthe same temperature as the dry gas) and also because the liquid of thedroplets absorbs the heat required for vaporization at a constanttemperature (assuming a constant pressure); Instantly upon the change intemperature of the contents oi. the bulb or boiler" is there is acorresponding drop in pressure which makes itself manifest in thechamber it of the expansion valve, thereby permitting the spring H tomove the valve 9 toward its seat. thus decreasing the amount oi liquidwhich enters the expansion coil I 5 per unit of time and thus restoringthe conditions in the coil is and suction pipe it to normal, that is tosay, to the condition 0! dry or superheated gas or vapor.

It has heretofore been common to try to maintain proper conditions inthe suction line by the use 01' hand operated expansion valves; by theuse of thermo-valves; pressure reducing valves, or float valves, orcombinations thereof. However, hand operated valves require constantattention and are not readily regulated to produce optimum results; therate of feed by a thermal valve is determined by the temperature of thesuction line and little adjustment is made for changes in pressure; andpressure reducing valves work only on suction line pressures and make noallowance for temperature changes. It is thus dlilicult, with previoustypes of control valve to maintain aproper suction gas quality. Inaccordance with the present invention, the deficiencies of previoustypes of apparatus have been substantially eliminated. In the presentapparatus only liquid can be fed to the expansion coil-no liquid is fedwhen the machine is idle; and when liquid is being fed it is socontrolled that the gas in the suction line is definitely maintained ata dry saturated condition so that, the compressor is enchanges inpressure.

- abled to do a maximum amount of work, and thus the machine will workat its most emcient point for a given pressure diflerential.

In Fig. 3 a slight modification of the control apparatus is illustratedwherein the pipe 24 which leads to the expansible-contractible chamberof the expansion valve V leads from a hollow-walled cup is which is setinto a chamber formed by an upward bulge H in the suction pipe iI.Within this hollow-walled cup which constitutes the ,boiler there isplaced a conventional car-' tridge type electrical heating unit 2 Iwhich may be connected to the secondary 22 of the transformer 23, in thesame way as the coil 2| 0! Fig. 1; or to the line voltage. It isunderstood that the tube 24 and the hollow-walled cup it will be filledwith the volatile fluid and that this fluid will be maintained at aconstant temperature differential by means of the unit 2|". Pressureinside of the bellows iii changes with suction pressure and partiallycompensates for change in the dry saturated temperature of the gas withIn Fig. 4 a further slight modification is illustrated wherein thesuction pipe is is furnished with an upward bulge l'l providing achamber within which is housed a "boiler" comprising a spiral coil orbulb of capillary tubing which communicates with a pressureresponsiveelement, for example a sensitive Bourdon tube of a pressure-actuatedcurrent controller, for instance a variable resistance, impedance or aswitch P. The spiral coil or bulb i8 and the tube 24 are filled withvolatile fluid and when the temperature of the spiral bulb 18 is variedthe switch device P is thereby actuated. The bulb l8 is a tubularresistance coil of metal and is connected in series with the secondary22 of a transformer 23. The primary 28 oi this transformer is connectedto a supply line in the same way as the primary of the transformer 23 ofFig. 1. Connected in parallel with this primary 28 is the switch deviceP and the primary 33 of a I second transformer 34. The secondary 01'this latter transformer is connected in series with a thermallyresponsive motor device T which may be of the type disclosed, forexample in the copending application of Turner, Serial No. 506,439,filed October 15, 1943. now Pat. No. 2,433,493, issued December 30,1947, and which actuates the expansion valve B of the refrigeratingsystem.

In each of the devices shown in Figs, 3 and 4, the arrangement of thebulb within the suction pipe is such as to avoid any possibility-oiaccumulation of liquid in the suction pipe in the vicinity oi the bulb.As shown, the arrangement of Fig. 3 responds solely to temperature andno provision is shown for varying the heatsupply to the bulb inaccordance with variations insuction pressure, but it is manifest thatsuch pressure- In Fig. 5 a simpler type of arrangement is shown whereinthe presence of liquid drops in thegaseous medium is merely indicatedvisually without any provision for control of fluid conditions. Inthisarrangement the bulb i8 is arranged in the casing H in the suctionline as before. However, this bulb is a thin-walled metal cylinder orboiler of a material which is highly resistant to the flow ofelectricalcurrent and the ends of this cylindrical boiler are connectedin series with the secondary 22 of the transformer 13. The interior ofthis boiler II is connected by a capillary tube 24 to one vertical legof the manometer M. The manometer tube may contain a suitable liquid,for example oil or mercury, and the rise and fall of this liquid in theother leg of the tube may be noted by reference to a scale 31. When theliquid level stands above a predetermined point on the scale, the oprator is assured that the gas in the suction line is dry or superheated,but if the liquid level fall, the observer will known that droplets ofliquid are impacting the boiler W and will thus be warned to correctthis condition.

In Fig. 6 a still further modification is illustrated designed torespond with extreme sensitiveness. In this instance the tubularresistance coil or bulb or boiler I8 is of small thinwalled capillarymeta1 tubing one end of which is connected to or integral with one legof the manometer M. The manometer is filled with some opaque or coloredliquid which does not mix with the volatile fluid within the coil I8 andthe opposite leg of the manometer is placed in the path of a beam oflight from a light source 38, the beam being directed, if desired, by alens 39. At the opposite side of the manometer tube this beam of lightpasses through a diaphragm l and impinges upon a photoelectric cell 4|which is connected into an amplifying circuit in an amplifier mechanism42. The amplified current from this amplifier operates a relay 43 whichin turn controls the operation of a motor 44 which may be designed tooperate any desired type of apparatus, for example, the expansion valveof the refrigerating system. When the temperature of the spiral bulb I8varies by even the slightest degree, the level of the liquid in the freeend of the manometer tube will change slightly, thus varying the amountof light falling on the photoelectric cell II and thus causing actuationof the motor.

Obviously, instead of the manometer M, a pressure-responsive device likethe instrument P of Fig. 4 may be connected to bulb l8, and the device Pconnected to the amplifier 42 so that current variations induced in theinstrument P will be made available to control the motor.

In Fig. 7 an arrangement is shown wherein the thermally sensitive bulbor boiler l8 within the casing I! in the suction line is refrigeratedrather than heated. This bulb l8 may, for example, contain a gas whichexpands and contracts very rapidly with change in temperature and itsinterior is connected by tubes 24" and 24 to the oppositeends of=a coil45 placed in a refrigeratlng tank 46 containing a liquid which is keptat a predetermined temperature by a circulating refrigerant in a coil46. The apparatus is so set that the normal temperature of the bulb I8is slightly below the normal temperature of the gaseous medium flowingin the suction line ii. If under these circumstances droplets of liquidimpinge upon the bulb I8 the temperature will be quickly raised and thusthe pressure of the gas in the bulb will be varied. A capillary tube 41leads from the bulb I8 to the expansible-contractible chamber of themotor of the expansion I valve so that changes in pressure within thebulb ll cause a proper operation of the expansion valve to correctimproper conditions in the suction line. I

In Fig. 8 the pressure temperature curves for two common refrigeratingfluids are shown. One of these curves 48 is that for ammonia gas, andthe other 494s for methyl chloride. These are the curves for constantquality, to wit, the dry saturated condition. It is manifest that inorder for apparatus such as above described to operate accurately andproperly, so as to always maintain optimum working conditions in thesystem, it is necessary that the heat supplied to the sensitivelyresponsive bulb l8 be varied in accordance with variations in pressurein the suction line. As above pointed out, pressure variations are socompensated for by the provision of the pressure responsive controller25. However, it is possible under certain circumstances, where, forexample, the pressure normally'variesbut little during the operation ofthe apparatus, to dispense with this pressure control of the heat supplyand merely to supply a substantially constant amountof heat to the bulbl8 by the use of proper electrical resistors or impedances.

The apparatus has been described with particular reference toapplication of the basic principle to refrigeration. However, it iscontemplated that generally similar apparatus, operating on the sameprinciple, may be used, for instance in regulating the quality of steam,in a steam supply main, or for determining or controlling the presence.or amount of dust or other solid particles in a gas, and while certaindesirable embodiments and utilities of the invention have beenillustrated by wayof example, it is to be understood that the inventionis not necessarily limited to these precise embodiments or uses but isto be regarded as broadly inclusive of any and all modifications andapplications of the basic principl falling within the terms of theappended claims.

I claim:

1. In combination with a container for a gaseous medium in which solidor liquid particles may at times be suspended, a boiler within thecontainer, said boiler being filled with a volatile fluid, a devicewhich is sensitively responsive to change in pressure in said volatilefluid, and heatexchange means operative, so long as the condition ofthe-gaseousmedium is at a predetermined normal, tomalntain apredetermined temperature dlflerential between the contents of theboiler and the gaseous, medium, and means 101' regulating theheat-exchange means in response. to change in pressure of the gaseousmedium..

2. In combination with a conduit through which flows vapor in whichsolid or liquid particles may at times be suspended, a hollow bulbwithin the conduit containing a volatile liquid, electrically energizedheating means for the contents of the bulb, means for controlling thesupply of electrical energy proportionately to the pressure o! the vaporthereby normally to main tainthe bulb at a temperature slightly abovethe corresponding dry saturated temperature of the vapor, thetemperature of the bulb tending to change when the bulb is impacted byliquid particles entrained in the vapor, and motor means whose rate ofoperation varies in response to ghanges in temperature of the contentsof the ulb.

3. In combination with a conduit through which flows vapor in whichsolid or liquid particles may at times be suspended, a hollow bulbwithin the conduit containinga volatile liquid, electrically energizedheating means for the contents of the bulb, and means for varying theintensity of the heating current, said latter means being sensitivelyresponsive to the pressure of the vapor in the conduit and therebynormally maintaining the bulb and the volatile liquid a few degreesabove the dry saturated or superheated temperature of the vaporcorresponding to the instant pressure, the bulb and its contents beingcooled when the bulb is impacted by liquid particles entrained by theflowing gaseous medium,

and motor means responsive to variations in the temperature or thecontentsor the bulb, and a valve for varying the rate of flow of thevapor through the conduit, said valve being controlled by the motor. I

4. In a system wherein a gaseous medium is propelled through a conduitby a motor driven pump, a valve for modifying the rate of flow andthereby the pressure of the gaseus medium'in the conduit, a hollow bulbwithin the conduit, a fluid pressure motor for adjusting the valve, saidmotor having an expansible-contractible chamber, means providing apassage connecting the interior of the bulb with the motor chamber, aportion at least of the passage being constituted by a length ofcapillary tubing, the bulb, passage and motor chamber being normallyfilled with a volatile liquid, means for electrically heating thecapillary tubing and thereby the volatile liquid, is pressure-responsivecurrent regulator operative in response to pressure variations in theconduit to determine the intensity of current supplied for heating thecapillary tubing, the parts being so designed and arranged as normallyto maintain the temperature ofthe volatile liquid slightly above thetemperature of the gaseous medium corresponding to the instant pressure,and means for concomitantly controlling the current for actuating thepump motor and heating circuit.

5. In combination with a conduit through which flows a gaseous mediumwhich at times may contain suspended liquid particles, a hollowbulbwithin the conduit and in thepath of the gaseous medium, a coil ormetallic capillary tubi9 rent in the circuit heats the coil, and meansnormally maintaining such a current intensity as to heat the coil andthe volatile liquid to a temperature slightly in excess of the drysaturated or superheated temperature of the gaseous medium in theconduit, the impact upon the bulb of liquid particles entrained by thegaseous medium lowering the temperature of the bulb and thereby causingoperation of the motor and adjustment of the valve.

6. In combination with a conduit through which flows a gaseous mediumwhich at times may contain suspended liquid particles, a hollow bulbwithin the conduit and in the path of the gaseous medium, a containerhaving a thin metallic shell, means providing a. passage leading fromthe container to the bulb, means operative to cause electrical currentto traverse the shell of the container thereby to heat it, the bulb,con- REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS" Number Name Date 1,314,249, Crowell Aug. 26, 19191,709,468 Fassett Apr. 16, 1929 1,874,520 Hebler' Aug. 30, 19322,112,038 McLene'gan Mar. 22, 1938 2,112,750 Price Mar. 29, 19382,112,791 Small et al Mar. 29, 1938 Holmes Aug. 4, 1942

